Unsupported Operand Types?

[Seagull One]

I'm writing some code for my robot's stereoscopic vision.

This is how I'm calculating the stereo vision in python (I'm using the roborealm API).

COGXR = rr.GetVariable("COG_X_RIGHT")
COGYR = rr.GetVariable("COG_Y_RIGHT")
COGXL = rr.GetVariable("COG_X_LEFT")
COGYL = rr.GetVariable("COG_Y_LEFT")

Z_Actual = (11 * 5.5)/COGXL-COGXR
X_Actual = (COGXL*Z_Actual)/(5.5)
Y_Actual = (COGYL*Z_Actual)/(5.5)

Whenever I run the program however, I get this error message:

Traceback (most recent call last):
  File "C:\Python25\Lib\site-packages\pythonwin\pywin\framework\scriptutils.py", line 310, in RunScript
    exec codeObject in __main__.__dict__
  File "C:\Users\Loren\Desktop\My Robots\RoboRealm\API\API\Python\SteroTestNINA.py", line 289, in <module>
    Z_Actual = (11 * 5.5) / rr.GetVariable("COG_X_LEFT") - rr.GetVariable("COG_X_RIGHT")
TypeError: unsupported operand type(s) for /: 'float' and 'str'

This doesn't make much sense to me because COGXR and COGXL are not actually float or string variables. They come up as integers whenever I "print" them regularly. But for some reason when I stick them in an equation like this it wants to treat it as a float or a string.

Any idea's what I'm doing wrong?

BTW, haven't been to daniweb in a while

[xav.vijay]

what is the value of COGXR??

Can u give

print COGXR

before the Z_Actual thing and see what the output is?

[Seagull One]

Yes.

Apparently, COGXR equals "33"

Here's what it looks like before the exception is raised

Width:  160 Height:  120
IMAGE_COUNT = 541
33
Traceback (most recent call last):
  File "C:\Python25\Lib\site-packages\pythonwin\pywin\framework\scriptutils.py", line 310, in RunScript
    exec codeObject in __main__.__dict__
  File "C:\Users\Loren\Desktop\My Robots\RoboRealm\API\API\Python\SteroTestNINA.py", line 291, in <module>
    Z_Actual = (11 * 5.5)/COGXL-COGXR
TypeError: unsupported operand type(s) for /: 'float' and 'str'

Any ideas what's wrong?

[xav.vijay]

I guess your output is in string.

try

Z_Actual = (11 * 5.5)/float(COGXL)-float(COGXR)

[Seagull One]

Okay, I tried that, but now I'm getting this:

Width:  160 Height:  120
IMAGE_COUNT = 274

Traceback (most recent call last):
  File "C:\Python25\Lib\site-packages\pythonwin\pywin\framework\scriptutils.py", line 310, in RunScript
    exec codeObject in __main__.__dict__
  File "C:\Users\Loren\Desktop\My Robots\RoboRealm\API\API\Python\SteroTestNINA.py", line 291, in <module>
    Z_Actual = (11 * 5.5)/float(COGXL)-float(COGXR)
ValueError: empty string for float()

[xav.vijay]

ok...
what do get if u ..

print float(COGXL)
print float(COGXR)

before the calculations.

Ur error message says one of them is empty.

[Seagull One]

Thanks for the tips, xav.vijay!

The code is working and I'm getting some stereo vision responses from my robot!